1. Field of the Invention
The present invention relates to a method of controlling an automobile, an automobile control apparatus, a transmission a control apparatus for a transmission and a vehicle system, and in particular to a method of controlling an automobile, an automobile control apparatus, a transmission, a control apparatus for a transmission and a vehicle system which are appropriate for controlling an automatic transmission in a vehicle.
2. Related Art
An automobile incorporating a manual transmission is excellent in fuel consumption in comparison with an automobile incorporating a transmission using a torque converter. However, the associating operation between a clutch and an accelerator has been difficult upon a start of the automobile. Should this associating operation between the clutch and the accelerator be unsuccessful, a large shock would occur upon engagement of the clutch upon a start, or should the clutch pressure be insufficient, the engine speed would abruptly increase, that is, the so-called engine blow-up would be caused. Further, should the clutch be abruptly engaged when the engine speed is relatively low, or should the automobile be started on a slope, the engine would come to a stop, that is, the so-called engine stall would occur.
In order to eliminate the above-mentioned problem, there has been developed a system which uses a mechanism of a manual transmission in which the clutching operation and the gear change are automated, that is, an automated manual transmission (AMT).
However, the control upon a gear change with a conventional automated manual transmission would cause occurrence of cut-off of torque upon disengagement or engagement of the clutch, and as a result, the passenger would feel discomfort.
Accordingly, in order to avoid occurrence of cut-off of toque during a gear change, as disclosed in, for example, JP-B2-2703169, there has been known an automobile installed thereon a conventional automated transmission which incorporates an assist clutch serving as a transmitted torque changing means so as to control this assist clutch upon a gear change in order to effect engine speed synchronization and torque transmission.
In such an automobile, when a gear shift is started, at least a part of a torque inputted to a transmission is transmitted through the assist clutch in order to release a gear train through which a torque is transmitted by a meshing transmission means, and accordingly, the gear release is carried out in order to shift the meshing transmission means to a release position for release thereof. In order to carry out the gear release with no shock, a substantial part of an input torque should be transmitted by means of the assist clutch in order to shift the meshing transmission means to the release position for releasing gears with such a timing that the transmission torque through gear train is sufficiently released. Thus, after a lapse of a predetermined time from the time of a start-up of operation of the assist clutch is detected, a load is applied in a direction in which the meshing transmission means is shifted toward the release position, in order to carry out the control of gear release.
In order to carry out the gear release with no shock, it is required to transmit a substantial part of an input torque through the assist clutch, and then to shift the meshing transmission means to the release position with such a timing that the transmission torque through the gear train is sufficiently released. However, the start-up of operation of the assist clutch would be uneven due to unevenness among transmissions, aging effects or the like, and should the gear release be carried out with a timing deviated from an optimum timing, a stepwise torque difference would occur, and as a result, the gear change feeling would be unsatisfactory.
Thus, the applicant proposed, in JP-A-2002-174335, such an automatic transmission that a torque transmitted through the assist clutch is estimated or detected with the use of a sensor in order to detect an optimum timing for gear release, with which the torque transmitted through the gear train is sufficiently released, in accordance with the estimated or detected torque transmitted through the assist clutch, and accordingly, the meshing transmission means is shifted to the release position with this detected optimum timing.
However, the method proposed in the JP-A-2002-174335, an additional sensor is required so as to cause a problem of increasing the cost of the apparatus.